1. Field of the Invention
The invention disclosed relates to electric vehicle supply equipment.
2. Discussion of the Related Art
Plug-in electric vehicles (EVs), including all-electric cars, neighborhood electric vehicles and plug-in hybrids, are becoming a popular mode for personal transportation, in part because they are less expensive to operate and have a reduced carbon footprint. To support the increased number of EVs, more charging stations with more charging capacity must be made available. A typical commercial or residential electric vehicle charging station, also called an Electric Vehicle Supply Equipment (EVSE), has a single charging port to which may be connected a charging cable. The charging cable has a charging handle at its other end, whose connectors are inserted into a vehicle inlet for delivering electric power from the premises wiring to the electric vehicle. Only a single electric vehicle may be connected at a time to the charging port of the typical EVSE. The EVSE charging capacity is limited by circuit breakers and branch circuits of the installed infrastructure upstream of the EVSE, as well as the capacity rating of the EVSE itself.
A system is needed to allow increasing the number of available charging ports of an EVSE installation, without requiring an increased system capacity, and without requiring modification of the installed infrastructure upstream of the EVSE, such as rewiring the user's residence. Attempts have been made in the past to address this need by providing an EVSE add-on adapter with multiple charging ports that are sequentially powered. However, such a solution imposes a wait time for those EVs that are not first in line to be charged. Other attempts have required separate branch circuits to power each charging port of a multi-port EVSE.